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An electric double layer capacitor is composed of a pair of current collectors, a positive polarizable electrode provided on one of the pair of current collectors, a negative polarizable electrode provided on the other of the pair of current collectors, a separator between the positive and negative

An electric double layer capacitor is composed of a pair of current collectors, a positive polarizable electrode provided on one of the pair of current collectors, a negative polarizable electrode provided on the other of the pair of current collectors, a separator between the positive and negative polarizable electrodes, and an organic electrolytic solution which impregnates at least the positive and negative polarizable electrodes and the separator. The capacitor has a theoretical amount of ions Qt defined as description="In-line Formulae" end="lead"Qt (moles)=C횞V첨96,500,description="In-line Formulae" end="tail" wherein C is the rated capacitance (farads) of the capacitor and V is the rated voltage (volts), and an amount of ions Qe in the organic electrolytic solution, such that Qe/Qt=1.7 to 3.5. The capacitor has a high voltage rating, excellent cycle characteristics during high-current charging and discharging, and a low internal resistance in low-temperature environments.

대표청구항 ▼

The invention claimed is: 1. An electric double layer capacitor having a rated capacitance (farads), comprising: a pair of current collectors, a positive polarizable electrode provided on one of the pair of current collectors, a negative polarizable electrode provided on the other of the pair of cu

The invention claimed is: 1. An electric double layer capacitor having a rated capacitance (farads), comprising: a pair of current collectors, a positive polarizable electrode provided on one of the pair of current collectors, a negative polarizable electrode provided on the other of the pair of current collectors, a separator interposed between the positive and negative polarizable electrodes, and an organic electrolytic solution which impregnates at least the positive and negative polarizable electrodes and the separator; which capacitor has a theoretical amount of ions Qt defined by formula (I) below description="In-line Formulae" end="lead"Qt (moles)=C횞V첨96,500 (I),description="In-line Formulae" end="tail" wherein C is the rated capacitance (farads) of the capacitor and V is the rated voltage (volts) representing the maximum voltage allowed across the capacitor, and an amount of ions Qe in the organic electrolytic solution which impregnates the positive and negative polarizable electrodes and the separator, such that the ratio Qe/Qt is from 1.7 to 3.5. 2. The electric double layer capacitor of claim 1, wherein the positive polarizable electrode has a void volume V+ and the negative polarizable electrode has a void volume V-, such that the ratio V-/V+ is from 1.0 to 2.5. 3. The electric double layer capacitor of claim 1, wherein the positive polarizable electrode has a void volume V+, the negative polarizable electrode has a void volume V-, and the separator has a void volume Vs, such that the ratio (V++V-)/Vs is from 2.0 to 4.0. 4. The electric double layer capacitor of claim 1, wherein the volume Vp of the electrolytic solution which impregnates the void volumes of the positive and negative polarizable electrodes and the separator, and the total volume Va of the electrolytic solution present in the capacitor together satisfy the condition that Va/Vp is from 1.0 to 1.2. 5. The electric double layer capacitor of claim 1, wherein the organic electrolytic solution contains 0.9 to 1.8 mol/L of electrolyte. 6. The electric double layer capacitor of claim 1, wherein the organic electrolytic solution includes at least an ionic liquid of formula (1) below wherein R1 to R4 are each independently an alkyl group of 1 to 5 carbons or an alkoxyalkyl group of the formula R'--O--(CH2)n--(R' being methyl or ethyl, and the letter n being an integer from 1 to 4) and any two of R1, R2, R3 and R4 may form a ring together with X, with the proviso that at least one of R1 to R4 is the alkoxyalkyl group of the above formula; X is a nitrogen atom or a phosphorus atom; and Y is a monovalent anion. 7. The electric double layer capacitor of claim 1, wherein the separator is composed of glass fibers, polyolefin, polyamideimide or polyester, and has a porosity of 60 to 95%.